updated 03:16 am EDT, Tue June 5, 2012
Unlocking option available if baseband is old enough
Hackers the iPhone Dev-Team has updated the tools Ultrasn0w and RedSn0w, apps that allow users to jailbreak and in some cases unlock the iPhone 4 and 3G or 3GS. Ultrasn0w has been updated to version 1.2.7, which offers to jailbreak and then unlock an iPhone 4 -- with the catch that the baseband must be the older 01.59.00 (up-to-date iPhone 4 will be on baseband 04.12.01). The RedSn0w update makes it easier to implement or restore an untethered jailbreak.
The updates all focus around Apple's A4 and earlier devices, the iPhone 4 or earlier. Ultrasn0w will also unlock 3G or 3GS iPhone models that use basebands 04.26.08, 05.11.07, 05.12.01, 05.13.04 or 06.15.00, but not other versions. Late last month, a different group (Chronic Dev Team) released an app called Absinthe 2 that allowed A4 and A5 devices, even the latest iPhone and iPad, to be jailbroken without "re-tethering" (meaning the jailbreak was semi-permanent, and didn't need to be reinstalled after a power-down or reset). The only exception was the revised 2012 iPad 2 with the 32nm chipset, which remains resistant to the exploits used to jailbreak the other devices.
The updates represent the first successful unlocks of iOS 5.1.1, though they do require an older baseband that few users will have preserved. The updated RedSn0w will make it easier for owners of A4-based and earlier iOS devices to install the untethered jailbreak, which allows users to run unofficial apps. As the jailbreak is based on a flaw in iOS, the possibility of security risks or rendering the iPhone inoperative exists, though many users have accomplished the jailbreak successfully.
Unlocking, which is different from jailbreaking but requires the unit be jailbroken first, allows iOS devices to use microSIMs from carriers other than the ones users originally signed up with. Apple also sells unlocked iPhones, but at an unsubsidized price.
The new versions of RedSn0w are available for Mac and Windows. Simplified jailbreak tool PwnageTool has also been updated to version 5.1.1 to signify that it works with that iOS version. Ultrasn0w is available through the unofficial Cydia app repository, meaning a device must already be jailbroken in order to obtain it.